#include "TcpConnection.hpp"
#include "Logger.hpp"
#include "Channel.hpp"
#include "Acceptor.hpp"
#include "EventLoop.hpp"
#include "Socket.hpp"

#include <functional>
#include <strings.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>

static EventLoop* CheckLoopNotNull(EventLoop *loop)
{
    if(loop == nullptr)
    {
        LOG_FATAL("%s:%s:%d TcpConnection Loop is null! \n",__FILE__,__FUNCTION__,__LINE__);
    }
    return loop;
}

TcpConnection::TcpConnection(EventLoop *loop,
                const std::string &nameArg,
                int sockfd,
                const InetAddress& localAddr,
                const InetAddress& peerAddr)
    : loop_(CheckLoopNotNull(loop))
    , name_(nameArg)
    , state_(kConnecting)
    , reading_(true)
    , socket_(new Socket(sockfd))
    , channel_(new Channel(loop,sockfd))
    , localAddr_(localAddr)
    , peerAddr_(peerAddr)
    , highWaterMark_(64*1024*1024) //64M
{
    //下面给channel设置相应的回调函数，poller给channel通知感兴趣的事件发生了，channel会回调相应的操作函数
    channel_->setReadCallback(
        std::bind(&TcpConnection::handleRead,this,std::placeholders::_1)
    );
    channel_->setWriteCallback(
        std::bind(&TcpConnection::handleWrite,this)
    );
    channel_->setCloseCallback(
        std::bind(&TcpConnection::handleClose,this)
    );
    channel_->setErrorCallback(
        std::bind(&TcpConnection::handleError,this)
    );

    LOG_INFO("TcpConnection::ctor[%s] at fd=%d \n",name_.c_str(),sockfd);
}    

TcpConnection::~TcpConnection()
{
    LOG_INFO("TcpConnection::dtor[%s] at fd=%d state=%d \n",
        name_.c_str(),channel_->fd(),(int)state_);
}

void TcpConnection::handleRead(Timestamp receiveTime)
{
    int savedErrno = 0;
    ssize_t n = inputBuffer_.readFd(channel_->fd(),&savedErrno);
    if(n > 0)
    {
        //已建立连接的用户，有可读事件发生了，调用用户传入的回调操作onMessage
        messageCallback_(shared_from_this(),&inputBuffer_,receiveTime);
    }
    else if(n == 0)
    {
        handleClose();
    }
    else
    {
        errno = savedErrno;
        LOG_ERROR("TcpConnection::handleRead");
        handleError();
    }
}

void TcpConnection::handleWrite()
{
    if(channel_->isWriting())
    {
        int savedErrno = 0;
        ssize_t n = outputBuffer_.writeFd(channel_->fd(),&savedErrno);
        if(n>0)
        {
            outputBuffer_.retrieve(n);
            if(outputBuffer_.readableBytes() == 0 )
            {
                channel_->disableWriting();
                if(writeCompleteCallback_)
                {
                    loop_->queueInLoop(
                        std::bind(writeCompleteCallback_,shared_from_this())
                    );
                }
                if(state_ == kDisconnecting)
                {
                    shutdownInLoop();
                }
            }

        }
        else
        {
            LOG_ERROR("TcpConnection::handleWrite");
        } 
    }
    else
    {
        LOG_ERROR("TcpConnection fd=%d is down, no more writing \n",channel_->fd());
    }
}

//poller => channel::closeCallback => TcpConnection::handleClose
void TcpConnection::handleClose()
{
    LOG_INFO("TcpConnection::handleClose fd=%d state=%d \n",channel_->fd(),(int)state_);
    setState(kDisconnected);
    channel_->disableAll();

    TcpConnectionPtr connPtr(shared_from_this());
    connectionCallback_(connPtr); //执行连接关闭的回调
    closeCallback_(connPtr); //关闭连接的回调 TcpServer::removeConnection回调方法
}

void TcpConnection::handleError()
{
    int optval;
    socklen_t optlen = sizeof optval;
    int err=0;
    if(::getsockopt(channel_->fd(),SOL_SOCKET,SO_ERROR,&optval,&optlen)<0)
    {
        err = errno;
    }
    else
    {
        err = optval;
    }
    LOG_ERROR("TcpConnection::handleError name:%s - SO_ERROR:%d \n",name_.c_str(),err);
}

void TcpConnection::send(const std::string &buf)
{
    if(state_==kConnected)
    {
        if(loop_->isInLoopThread())
        {
            sendInLoop(buf.c_str(),buf.size());
        }
        else
        {
            loop_->runInLoop(
                std::bind(
                    &TcpConnection::sendInLoop,
                    this,
                    buf.c_str(),
                    buf.size()
                )
            );
        }
    }
}

/**
 * 发送数据 应用写的快 而内核发送数据慢 需要把待发送数据写入缓冲区，而且设置了水位回调
 */
void TcpConnection::sendInLoop(const void* data,size_t len)
{
    ssize_t nwrote = 0;
    size_t remaining = len;
    bool faultError = false;

    //之前调用过该connection的shutdown，不能再进行发送了
    if(state_ == kDisconnected)
    {
        LOG_ERROR("disconnected, give up writing!");
        return;
    }

    // 表示channel_第一次开始写数据，而且缓冲区没有带发送的数据
    if(!channel_->isWriting() && outputBuffer_.readableBytes()==0)
    {
        nwrote = ::write(channel_->fd(),data,len);
        if(nwrote >= 0)
        {
            remaining = len - nwrote;
            if(remaining == 0 && writeCompleteCallback_)
            {
                //既然在这里数据全部发送完成，就不用再给channel设置epollout事件了
                loop_->queueInLoop(
                    std::bind(writeCompleteCallback_,shared_from_this())
                );
            }
        }
        else //nwrote < 0 出错
        {
            nwrote=0;
            if( errno !=EWOULDBLOCK) //EWOULDBLOCK由于非阻塞没有返回
            {
                LOG_ERROR("TcpConnection::sendInLoop");
                if(errno == EPIPE || errno == ECONNRESET) //SIGPIPE RESET
                {
                    faultError = true;
                }
            }
        }
    }
    
    /**
     * 说明当前这一次write,并没有把数据全部发送，剩余的数据需要保存到缓冲区当中，然后给channel
     * 注册epollout事件，poller发现tcp的发送缓冲区有空间，会通知相应的sock-channel，调用writeCallback_回调方法
     * 也就是调用TcpConnection::handleWrite方法，把发送缓冲区的数据全部发送完成
     */
    if(!faultError && remaining > 0)
    {
        //目前发送缓冲区剩余的待发送数据的长度
        size_t oldLen = outputBuffer_.readableBytes();
        if(oldLen + remaining >= highWaterMark_ 
            && oldLen < highWaterMark_
            && highWaterMarkCallback_)
        {
            loop_->queueInLoop(
                std::bind(highWaterMarkCallback_,shared_from_this(),oldLen+remaining)
            );
        }
        outputBuffer_.append((char*)data+nwrote,remaining);
        if(!channel_->isWriting())
        {
            channel_->enableWriting(); //这里一定要注册channel的写事件，否则poller不会给channel通知epollout
        }

    }
}

//连接建立
void TcpConnection::connectEstablished()
{
    setState(kConnected);
    channel_->tie(shared_from_this());
    channel_->enableReading(); //向poller注册channnel的epollin事件

    //新连接建立，执行回调
    connectionCallback_(shared_from_this());
}

//连接销毁
void TcpConnection::connectDestroyed()
{
    if(state_ == kConnected)
    {
        setState(kDisconnected);
        channel_->disableAll(); //把channel的所有感兴趣的事件，从poller中del掉
        connectionCallback_(shared_from_this());
    }
    channel_->remove(); //把channel从poller中删除掉
}

//关闭连接
void TcpConnection::shutdown()
{
    if(state_ == kConnected)
    {
        setState(kDisconnecting);
        loop_->runInLoop(
            std::bind(&TcpConnection::shutdownInLoop,this)
        );
    }
}

void TcpConnection::shutdownInLoop()
{
    if(!channel_->isWriting()) //说明outputBuffer中的数据已经全部发送完成
    {
        socket_->shutdownWrite(); //关闭写端
    }
}
    